Our work - Turning waste heat into electricity
Our Work is a post series that talks about our past or current work in a specific area or industry.
The concept for converting waste heat or heat from low temperature sources has been around for years. One of the classic usages has been geothermal heat sources. This has been accomplished using binary cycle systems. Hot water (350 degree F) from some (usually deep) geothermal source is pumped to the surface and used to heat a fluid, such as butane, which then flows through a turbine to generate electricity. However the efficiencies have been moderate and if it weren't for the free heat source the technology would barely be cost effective (providing a reasonable return on investment). Some industry efforts have improved these efficiencies and lowered the feasible working temperatures to improve the possibilities for this kind of technology and increasing the potential applications. For geothermal this means shallow less expensive wells with lower temperature water could be used for energy sources.
KVA has made significant improvements in converting low temperature and waste heat into energy. KVA's initial improvements were driven by the need to improve the output efficiency of a municipal Plasma Waste Converter system. This unique waste conversion process generates a considerable amount of waste heat of which only a small amount gets reclaimed. These initial efforts to reclaim this heat and increase efficiencies demonstrated that additional gains were possible not only in efficiency, but in lowering the required working temperature of the medium, making very low grades of waste heat potential sources of electricity. KVA is working to produce cost effective prototypes suitable for converting heat from very low grade sources such as cooling towers or refrigeration condensers.
There are several potential impacts of this technology
Freeing millions of acre feet of water currently used in cooling towers for other uses.
Increasing the efficiency of existing power plants. In many parts of the country coal power plants were built at the mouth of the coal mines to eliminate the transport cost of the coal. However, in many of these regions, water for cooling towers was limited and this limitation defined the size of the power plant. With this technology, the need for the water could be reduced or eliminated, resulting in an increase in the net output of the power plant and freeing up scarce water for other uses. The same potential also applies to nuclear power plants.
Providing additional distributed power. All over the world, thousands of industrial companies spend large sums of money on equipment to dispose of process waste heat or refrigeration waste heat (from the condensing cycle). Almost all of this equipment consumes electricity and requires considerable maintenance and monitoring. This technology could be applied in these settings to reduce plant operations costs and generate additional electricity from this waste heat.
Making increased use of more low grade heat sources and shallower (less expensive to reach) geothermal sources
